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Research Papers

Offset Slices for Multidirection Layered Deposition

[+] Author and Article Information
Prabhjot Singh

 General Electric Global Research, Niskayuna, NY 12309singh@research.ge.com

Debasish Dutta

Department of Mechanical Engineering, University of Michigan, Ann Arbor, Ann Arbor, MI 48109dutta@umich.edu

J. Manuf. Sci. Eng 130(1), 011011 (Feb 15, 2008) (12 pages) doi:10.1115/1.2783217 History: Received February 24, 2004; Revised July 29, 2007; Published February 15, 2008

Layered Manufacturing (LM) techniques build a part by adding thin layers of material. In this process, overhangs need to be supported by sacrificial supports, resulting in an increase in the build time, wastage of material, and costly post-processing. Metal-based LM machines with the capability to deposit material along multiple directions resolve most of the above problems. Importantly, these machines can deposit nonplanar slices. In this paper, we study such slices and present a task framework for their use with multidirectional layered deposition machines. The aim of the analysis is to identify part subvolumes that can be built using nonplanar slices for a process-dependent overhang angle. Solution methodologies for 2D, extruded parts, and general 3D parts are presented. Algorithms and illustrative example parts are included.

Copyright © 2008 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

(a) Deposition nozzle mounted on a robot arm and (b) multidirection deposition configuration with a rotating deposition table and a translating deposition nozzle schematic

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Figure 2

(a) Part and the base surface and (b) offsets of the base surface used to deposit the part

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Figure 3

Simple setup for the deposition of nonplanar slices

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Figure 4

Multidirection deposition: decomposition of a part into subvolumes

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Figure 5

Multidirection slicing

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Figure 6

(a) Part and (b) MDS decomposition, V2 has a nonplanar base, which cannot be deposited using planar slices

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Figure 7

(a) Decomposition, with the transition zone shown in dark, and (b) enlarged view of the transition zone deposited using offset slices

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Figure 8

(a) Part model, (b) processed volume, (c) unprocessed volume, and (d) deposition using offset slices

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Figure 9

Offset slices for depression features: (a) MDLD decomposition of the input part along B and (b) deposition using offset slices

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Figure 10

Offset slices for protrusion features: (a) MDLD decomposition of the input part volume along B and (b) deposition using offset slices

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Figure 11

Solving Eq. 6 inside a Voronoi cell

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Figure 12

Approximation of a degree-4 NURBS curve using circular splines

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Figure 13

Extrusion of a planar profile, P(u) along [Tx(v),Tx(v),z(v)]

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Figure 14

The construct of the overhang angle equation (Eq. 10) comprising of the normal to the offset of the base surface composed of a circular arc and the part surface, at their point of intersection

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Figure 15

Computation of the boundaries of the unbuildable part volume—2D

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Figure 16

(a) Input part volume and (b) buildable and unbuildable part volumes

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Figure 17

(a) Base curve and (b) the unprocessed subvolume—in profile. The point at which the overhang is exceeded is shown.

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Figure 18

(a) The decomposition of the part - subvolumes 1 and 2 are unprocessed. Subvolumes 3 and 4 are processed subvolumes and (b) offset slices are used to deposit the processed subvolumes.

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Figure 19

(a) The part to be built, along the initial orientation B (b) the processed and unprocessed subvolumes of the part, along B

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Figure 20

(a) Annular region in profile (b). The Voronoi diagram of the region bounded by the dashed red line.

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Figure 21

(a) Region of interest and (b) the overhang angle constraint is violated at points P1 and P2

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Figure 22

The region of interest in Fig. 2 is divided into buildable and unbuildable regions

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Figure 23

(a) The part with the assigned build direction and (b) the MDS decomposition of the part composed of Pbuild and Punbuild

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Figure 24

(a) The points at which the overhang angle condition is violated and (b) the decomposition of the part into Pbuild and Punbuild for offset slice deposition

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Figure 25

(a) An example with a 3D base surface and (b) the corresponding MDS decomposition along (0, 0, 1)

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Figure 26

(a) Discretization of the part and base surfaces for level set computation. The unbuildable surface region on the part boundary is represented by filled circles (b) Computation of the unbuildable part volume—discrete.

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Figure 27

The unbuildable part volume when slices are offsets of the base surface

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